Internal combustion engine shut-down for engine having adjustable valves

Abstract

A method for operating an engine in a vehicle, the engine having at least a cylinder, is described. The method comprises decreasing rotational speed of the engine; and when said engine speed falls in a specified region, adjusting a valve timing of the cylinder to generate one of expansion or compression braking torque to stop rotation of said engine in a desired range.

We claim: 
     
       1. A method for operating at least one of an intake valve and an exhaust valve of an engine, the engine including a plurality of cylinders, each of the plurality of cylinders including a piston, the method comprising:
 during conditions of an engine shut-down, monitoring engine rotation; and 
 when engine speed falls below a threshold value, repeatably stopping the engine with a selected piston in a selected stopped location by adjusting at least one of an intake or exhaust valve opening or closing, wherein said selected piston varies with operating conditions from one engine shut-down to another engine shut-down. 
 
     
     
       2. The method of  claim 1  wherein said selected location varies with operating conditions. 
     
     
       3. The method of  claim 1  wherein said one valve is an electrically actuated valve. 
     
     
       4. The method of  claim 1  wherein said one valve is an electrically actuated intake valve. 
     
     
       5. The method of  claim 1  wherein said one valve is opened and closed to generate one of engine expansion or compression braking torque. 
     
     
       6. The method of  claim 5  wherein other cylinders are operated with a valve held open throughout cycles of the cylinder. 
     
     
       7. The method of  claim 1  further comprising restarting the engine from said stopped piston location. 
     
     
       8. The method of  claim 1 , further comprising injecting fuel into the cylinder of the selected piston during an engine shut-down without combusting said fuel for use in a subsequent re-start of the engine. 
     
     
       9. The method of  claim 1 , wherein the selected stopped location is within a selected range. 
     
     
       10. A method for operating an engine in a vehicle, the engine having at least a first and second cylinder, said cylinders having at least an intake and exhaust valve, comprising:
 during conditions of an engine shut-down, monitoring engine operation; 
 when engine operation enters a specified region, repeatably stopping the engine in a selected stopped location by adjusting valve opening or closing operation of one of said intake and exhaust valves so that both said first and second cylinder generate one of expansion or compression braking torque; and 
 wherein other cylinder are operated with a valve held open or closed throughout cycles of the cylinder. 
 
     
     
       11. The method of  claim 10  wherein other cylinders are operated with a valve held open throughout cycles of the cylinder. 
     
     
       12. The method of  claim 10  wherein other cylinders are operated with valves held closed throughout cycles of the cylinder. 
     
     
       13. The method of  claim 10  wherein said valves are adjusted to repeatably stop the engine with a selected piston in a selected location. 
     
     
       14. The method of  claim 10  wherein an amount of valve adjustment varies with changes in ambient conditions of the vehicle. 
     
     
       15. The method of  claim 10  wherein an amount of valve adjustment varies with changes in engine speed. 
     
     
       16. The method of  claim 10  wherein an amount of valve adjustment varies with changes in engine position. 
     
     
       17. A method for operating an engine in a vehicle, the engine having at least a cylinder, the method comprising:
 decreasing rotational speed of the engine; and 
 when said engine speed falls in a specified region, stopping rotation of the engine in a desired range by adjusting at least an exhaust valve timing of the cylinder to generate one of expansion or compression braking torque. 
 
     
     
       18. The method of  claim 17  wherein said range is a desired stopping position. 
     
     
       19. The method of  claim 17  wherein an intake valve closing timing is further adjusted to generate one of expansion or compression braking torque. 
     
     
       20. The method of  claim 17  wherein said exhaust valve is electrically actuated, and only during selected conditions, fuel is injected during an engine shut-down for use in subsequent re-starts. 
     
     
       21. A method for operating an engine in a vehicle, the engine having at least a cylinder, the method comprising:
 during engine conditions above a first engine speed, adjusting valve operation in one or more cylinders to generate engine braking torque to reduce engine speed; and 
 during engine condition below a second engine speed, stopping the engine in a desired location by holding an intake valve or an exhaust valve closed throughout rotation of at least a substantial portion of a cycle of the engine.